Max mason



M. MASON.

DETERMINATION OF WAVE ENERGY DIRECTION.

APPLICATION FILED JUNE 25,1919.

IN VEN TOR.

2 SHEETS-SHEET 1.

Patentefi July 18, 1.922.

IVI. MASON.

DETERMINATION OF WAVE ENERGY DIRECTION.

APPLICATION FILED JUNE25. 1919.

1,422, 7 E Patented July I8, 1922,

2 SHEETS-SHEET 2.

INVENTOR. film M UNHTED TATE MAX MASON, OF NEW LONDON, CONNECTICUT,ASSIGNOR TO SUBMARINE SIGNAL COMPANY, OF PORTLAND, MAINE, A CORPORATIONOF MAINE.

DETERMINATION OF WAVE-ENERGY DIRECTION.

Specification of Letters Patent.

Application filed June 25, 1919. Serial No. aoaesse.

To all whom it may concern Be it known that 1, MAX Mason, a citizen ofthe United States, residing at New London. in the county of New Londonand State of Connecticut, have invented new and useful Improvements inDetermination of Wave-Energy Directions, of which the following is aspecification.

The present invention relates to the determination of wave energydirection, and more particularly to apparatus for determining thedirection from which the wave energy is coming, comprising a pluralityof receivers, normally disposed broadside to the wave front, andcompensated leads from the receivers to bring the energy into phase atthe place of utilization.

The present invention is specifically illustrated as embodied in devicefor determining the direction of submarine sounds in which a pluralityof receivers, disposed in a row, may be turned broadside to the soundsource. The invention, however, is not limited in application tosubmarine sound reception but may be employed for other purposes as Willbe apparent from the followingz description ferring to the illustratedembodiment of the invention, Fig. 1 is an elevation of submarinelistening device embodying the invention. Figs. 2 and 3 are a top planView and a side elevation of the receiver containing casing. Fig. 4 is afragmentary view showing a portion of the bottom of the receiver casing.Fig. 5 is an elevation, partially in section, of the receiver casing andits mounting post. Figs. 6, 7, and 8 are illustrative diagrams, and Fig.9 is a perspective view showing the assembly of the receivers andcollecting tubes.

The principles underlying the invention will first be explained withparticular reference to the diagrams shown in Figs. 6, 7, and 8. Let arow of sound receivers l, 2, 3, 4, 5, 6, 7, and 8 be disposed in astraight line in the water or other surrounding sound conducting medium.Let the several rcceivers be connected to a common collection point 10by means of air columns 9 which are all of the same length.

Then if sound strikes the receivers in a direction at right angles tothe row of receivers, the sound waves will be brought together in phaseat the collection point l() and the sound will be amplified. Suppose,

however. the sound comes from other direction. for example from theleft. either along the line of the receivers shown in Fig. (i or at someacute angle thereto. Then the sound will strike the receivers, 1, 2. 3.-l. etc. in succession and the sound waves transmitted through the tubeswill be brought successively to the collecting point 10. The waves willbe out of phase and interfere so that the sound will be greatly lessthan that heard for a wave striking the line of receivers broadside. Aline of receivers of the type for focusing sounds coming broadside istermed a beam compensated line. and if the paths for transmitting thesound from the receivers to the common collection point havepredetermined fixed lengths, the compensation is termed fixedcompensation. as contrasted with variable compensation in whichprovision is made for varying the length of the transmitting paths fromthe receivers.

In practice, it is found convenient to bring the energy from thereceivers together-progressively in a plurality of collection stages.Such arrangement is shown diagrammatically in Fig. 8. The soundsreceived by the receivers 1 and 2 travel over tributary branch paths ofequal length. 11 and 12. to a lead 21. Similarly the receivers 3 and 4-are joined through branch paths 13 and 1 to a lead 22. The leads 21 and22 are of the same length and join a lead 31. The receivers 5, 6, 7 and8 are similarly connected to a lead 32 which meets the lead 31 at ajunction point 33. to which is connected a stcthoscope 34. It will beseen from an inspection of the Fig. 8 that the paths from the severalreceivers to the stethoscope are all of the same length so that thewaves transmitted from the several receivers will all be brought intophase at the stethoscope. for wave fronts striking the line of receiversbroadside.

The diagrams of Figs. ('3 and 8 show arrangements in which the sounddirection is indicated by the iuaximum of sound observed when the row ofreceivers is turned broad side to the direction of the sound. Thedctcrminatiou of the maximum may be combin'ed with what is known as abinaural ccntering of the sound. The combination of receivers to achievethis is shown diagrammatically in Fig. 7. In Fig. T the receivers l, 2,3 and 4 are connected by branch paths Patented July 18, 1922. I

of equal length to the lead 31, and the receivers 5, 6, T and S, areconnected by branch paths of equal length to the end of the lead 32.Instead of having the leads 31 and 32 joined, they are connectedrespectively with the left and right ear pieces 35 and 36 of thestethoscope. The leads 31 and 32 are of equal length and the tubes ofthe two halves of the stethoscope are also of equal length. If a soundstrikes the row of receivers broadside, the sound waves from thereceivers 1, 2, 3, and 4 will all be brought into phase at the left ear,and the sound waves from the receivers 5, 6, 7, and 8 will all bebrought into phase at the right ear. Also the sounds coming into the twoears will be in phase with each other, so that the sound will appear tothe observer to be centered in a medium plane through the observershead, or is said to be binaurally centered. The arrangement shown inFig. 7 has the advantage that it combines binaural centering with asound maximum. Under some circumstances, however, it is found preferableto rely upon a maximum alone, without the binaural.

Suppose the row of receivers 1 to 8 inclusive are mounted so as to beturned in any direction. When the row. of receivers is turned so thatthe sound wave has a different time of arrival at the several receivers,the sound will be weak andblurred, but when the row is turned so thatthe sound comes from broadside, striking all the receivers at the sametime, the sound suddenly becomes clear and distinct, with greatlyincreased loudness. By turning the row of receivers back and forth thepoint of maximum loudness can be determined.

In case the receivers are connected to two halves of a listening devicefor binaural listening, if the row is turned so that the sound wavesarrive at one end of the row first, the sound will appear to be locatedin the corresponding ear of the observer. As the row of receivers isturned broadside to the sound, the intensity of the sound not onlyincreases, but the location of the sound appears to the observer totravel until it is centered with respect to the observers ears.

When branching air tubes are used for collecting the sounds from theseveral receivers, it is found that for the best. conservation of thesound, the cross sectional area of the air path through the tubes shouldbe conserved. For example, the lead 21 should have a cross sectionalarea equal to the sum of the cross sectional areas of the leads 11 and12. and the lead 31 should have a cross sectional area equal to the sumof the cross sectional areas of the leads 21 and 22. This prevents thereflection and loss of sound which would otherwise take place at asudden reduction or increase in the diameter of the sound paths. If forany reason a sound conducting tube must be changed in diameter, it

should be done by a gradual coning of the tube.

It is also important that the several receivers should be non-resonantfor the wave frequencies which are to be received. In the case ofsubmarine sound receivers placed at the ends of conducting air tubes,the par tition wall or diaphragm between the water and the air should bemade to have little, if any, natural frequency of its own, which liesnear the frequencies of sound to be received. Otherwise if the receiverdiaphragms start vibrating at their own natural frequencies such freevibrations will in general be out of phase and will cause interferencein the system.

In Figs. 1 to 5 inclusive, and in Fig. 9, is illustrated a beamcompensated rotatable listening device employed for determining thedirection of submarine sounds.

The branching air pipes to the several receivers is as shown in Fig. 9.The receivers thirty-two in number are secured to the ends of thirty-twoshort pipes 51, all of the same length. These pipes join in pairs tosixteen pipes 52, all of the same length, which in turn join eight pipes53, all of the same lengths. The pipes 53 join four pipes 54 all of thesame length. The ten pipes 54 at one half line join a pipe 55, while theten pipes 54 which are at the other half of the line join the pipe 56,thus connecting the receivers of one half of the line to pipe 55 andthose of the other half to pipe 56. These pi ass 55 and 56 are connectedto upright tu es 57 and 58, which as shown by the dotted lines in Fig. 5are gradually coned down to reduce the cross sectional area. However,coning may be omitted in some cases. The tubes 57 and 58 are connectedat the top to the two ear pieces respectively of a stethoscope 59.

As shown in Fig. 9 the size of the several air tubes is such that thecross sectional area of any two is equal to the sum of the crosssectional areas of its tributary branch tubes.

The receivers are shown as of the rubber nipple type. Referring to Fig.5 each receiver consists of a small nipple 61, of soft rubber, which isclamped with a watertight connection over the end of the tube 51. It isfound that rubber makes excellent material for the receiver walls inmaking a non-resonant receiver. While a receiver of the nip ple type isshown. receivers of other types have been used, for example receivers ofthe rubber button or diaphragm type.

The receivers with their branching collection pipes are housed in thecross arm 65 which is carried on the bottom of the post 66. The crossarm 65 is hollow and is provided with openings 67 through the bottom,through which the water has free access to the space around thereceivers. The sound waves in the water pass through the metal means ofa scale 7 O. The scale is calibrated to indicate the direction of thesound when the receivers are turned broadside to it, and enable theobserver, who is generally in the hold of the ship to immediatelydetermine the angular bearing of the sound source with respect to theships head. Itwill'be noted that a line of receivers with beam compen-'sation as here described will give a maximum response to sounds comingat right angles to its length, so that a maximum will be heard fromsound either directly in front or behind the line of receivers. Alsosounds directly in front or behind the line of receivers will bebinaurally centered. However, it is found that when a sound is in frontof the row of receivers, and the right hand section of the receivers isconnected to the right ear and the left hand section to the left ear,upon swinging the receivers throu h a small angle to the right thebinaural shift of the sound will be to the left, while if the sound iscoming from behind it will appear to shift to the right. By this meansthe ob server can quickly eliminate the 180 degree ambiguity ofdirection of the sound approaching from in front and from behind theline of receivers.

In the listening device illustrated in Fig; 9 there are thirty-tworeceivers, sixteen being connected to each car. It is found that themaximum or focus is much sharper when there are a considerable number ofreceivers connected so that the waves from them are brought into phasebefore entering the ear. For example, if two receivers are used, oneconnected with each ear, a binaural centering may be made but with noappreciable maximum. On the other hand if a plurality of receivers isconnected to each car as shown in the drawings, a maximum response aswell as a binaural centering will be obtained. In general, the greaterthe number of receivers, the sharper the maximum, the ultimate number ofreceivers of course being limited by mechanical construction and thelength of the collecting tubes. It is found that not only is the maximumof aid in determining the direction of sound, but is of great aid inthat it focuses out or minimizes sounds from interfering sources locatedat other angular bearings. For example, if the row of receivers isturned broadside to a particular sound source, the sound from suchsource will be loud and distinct, while sounds from sources having otherangular bearings will be weak and blurred. This gives the instrument thepower of discrimination in focusing on the desired sound, and focusingout or minimizing undesirable sounds. This is found of particularadvantagewhen there are a number of ships in the sound field and it isdesired to follow a particular ship to the exclusion of the others, andwhen there are interfering sounds from waves etc.

While the energy transmitting paths from the receivers to the placewhere the energy is utilized, (in the present case the stethoscope), areshown as air paths in the illustrated embodiment 'of the invention, itis obviousthat other transmitting means might be used. While theinvention has been described with particular reference to a device fordetermining the direction of submarine sounds, it'may be used fordetermining the direction of sources of other kinds of wave energy. Itis to be understood therefore that the present invention is not limitedto its illustrated embodiment but may be embodied in other structureswithin the scope of the following claims.

I claim:

1. In apparatus of the character described, the combination of: soundreceivers disposed in a row, divided into two sections of a series ofreceivers each, means for bodily turning the row of receivers, alistening device having two e'ar pieces, one for each ear of theobserver, and energy collecting means having branching tributary pathsbetween the receivers of each section and the corresponding ear piece ofthe listening device, the several paths all having the same time ofenergy travel from the receivers to J the listening device,substantially as described.

2. In apparatus of the character described, the combination of at leastfour sound receivers disposed in a row, means for bodily turning the rowof receivers, and means for collecting and utilizing the received waveenergy including two ear pieces, one for each ear of the observer, andenergy transmitting paths all having the same time of travel, for theenergy from the several receivers, substantially as described.

3. In apparatus of the character described, a combination of acousticreceivers disposed in a row, divided into two sections of a plurality ofreceivers each, means for bodily turning the row of receivers, alistening device having two ear pieces, and means for conducting thesound waves from the receivers to the listeningdevice, comprising airpaths all of the same acoustic length leading from the receivers of therespective sections to the respective ear pieces, substantially asdescribed.

4. In apparatus of the character described, the combination of theplurality of acoustic receivers, a listening device, and connectionsfrom the receivers to the listening device, comprising an air tubehaving tributary branches of equal length, each branch in turn havingtributary branches of equal length, andv so on, thelast set of branchesbeing connected to the receivers substantially as described.

5. In apparatus of the character described, the combination of aplurality of acoustic receivers, a listening device, and connectionsfrom the receivers to the listening device, comprising an air tubehaving tributary branches of equal length, each branch in turn havingtributary branches of equal length, and so on, the last set of branchesbeing connected to the receivers, the cross section of each tube beingsubstantially equal to the combined cross sections of its tributarybranches, substantially as described.

6. In apparatus of the character described, the combination of four ormore receivers of Wave energy disposed in a straight line, means forbodily turning the line of receivers and means for collecting andutilizing vice, means for turning the rowof receivers,

and means for obtaining a binaural centering together with a maximumresponse, comprising a binaural listening device having two ear piecesrespectively connected with the receivers of the respective sections bya plurality of wave conducting paths all of the same length,substantially as described.

MAX MASON.

